Offline server

If you're on Windows take a look ar EasyPHP - I have been using for several years, and find it a good set up for a local testing server. There are additional modules/add ons to for setting up things like local virtual hosts (which I find useful for working with multiple projects) and you can switch between PHP/Apache/MySQL versions if need be.

to complete what was said by @Nancy OShea and @osgood_ you'll find two nice tutorials on line, the first one on Adobe website

https://helpx.adobe.com/dreamweaver/using/set-testing-server.html

and a seond one, pretty old but nicely done...

https://www.w3information.com/how-to-setup-localhost-dreamweaver-windows#gsc.tab=0

I use Wamp Server on Windows.  The version of PHP & MySQL is compatible with my remote Linux/Apache server. 

After installing local server, define it in Dreamweaver by going to Site > Manage Sites.  See screenshots.

Local Site Folder:

Servers tab:

Basic

Advanced

Final

Hi
I have Dreamweaver 2020.

Is it possible in version 2020 to make an Offline server so I can see my work while I make a new website in PHP?

Would like to be able to see the finished work before I upload to the WebServer itself!

If "YES" Is there a good guide or video tutorial I can follow?

By @steenmikkelsen2

Not directly in Dreamweaver. There are free local server packages you can download like XAMPP, https://www.apachefriends.org/index.html which is popular for both PC and Mac and MAMP https://www.mamp.info/ which is popular on the Mac. Both contain a local server environment which can run php/sql plus has an sql interface called phpMyAdmin

There's nothing in Dreamweaver which will assist you to connect to a database and query that database to produce dynamic websites. There are a couple of paid for (commercial) extentions which are available for Dreamweaver https://www.webassist.com/product/mysqli or the other alternative is to watch a few Youtube videos.

Once you have a local server environment set up (search youtube for XAMPP set up. Make sure you find a video which is less than about 2 years old) then its not that difficult to write a few simple database queries which will get data and display it on your page, update it and delete it etc